In general, integrated circuit devices are tested or characterized during or after manufacturing to verify their functionality under various operating conditions. Such testing or characterization is usually performed by using Automatic Test Equipment (ATE). A typical ATE system includes a tester that has a number of hardware resources for performing specific functions, such as data generation, timing generation, voltage level generation, and data collection, etc. A processor/controller is typically used to program and control the tester hardware resources.
In some ATE systems, when performing sweep tests (e.g., timing sweeps, voltage level sweeps), the controller first programs the tester hardware resources with device parameter values that are associated with a particular test condition, or “sweep point.” The controller also provides the tester with a test pattern that can be used to verify a particular function of the device under test (DUT) at that sweep point. The tester then generates stimuli based on the test pattern and the device parameter values, applies the stimuli to the DUT and collects the responses of the DUT. Thereafter, the controller interrupts the tester to read the responses and to reprogram the tester hardware resources with device parameter values that correspond to another sweep point. This process is oftentimes repeated for a large number of sweep points. When tests covering all sweep points within a predefined sweep range are performed, a pass-fail boundary for the device can be extracted from the collected data. A decision to reject the DUT or to select an appropriate “bin” for the DUT can be made based on the pass fail boundary.
Depending on the length of the data stream used for each test, a disproportionate amount of time may be needed to reprogram the tester hardware resources. For example, the tester needs only 1.25 ms to apply a 1 Mbit stimulus at a data rate of 800 Mbps to the DUT. But it may take the controller up to 100 ms or more to interrupt the tester, to reprogram the tester hardware resources with new test patterns or new device parameter values, and to restart the stimulus burst. Because many sweep points are tested to fully characterize an integrated circuit device, the cumulative effect of this inefficiency is significant.
Accordingly, what is needed is an improved method and apparatus for testing or characterizing circuit devices.